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[rweust]

This is a trick I came across to solve a problem.

In my water gauge glass I had some trouble with bubbles disturbing a propper read out. This also occurred when the boiler was heated up and under pressure (3 bar, 50 PSI) and there shouldn't be air but only steam inside.
On a Dutch site somebody advised placing a very thin copper Litze wire in the water gauge glass. Such a wire as you can pull out of a household electrical cable.

I don't know how it works but in cold state the bubbles are gone (see pictures). Tomorrow I will make a test run in my pond and let you know if it works with the boiler heated up and under pressure.

Has anybody any idea if this works and how?

Robert.

[gondolier88]

It works perfectly in the gauge I did this on for a friend's Cheddar Puffin boiler- it works by removing the meniscus (look at water in any container, on the surface there is a thin 'skin' that rises up where it meets at the edges of the container, it is also the 'skin' that insects such as the Water Boatmen glide about on). When bubbles form in the water gauge they also have a meniscus at the bottom that is kept from joining the meniscus on the top of the actual water level by the pressure in the bubble. The wire draws the meniscus of the water up, and the meniscus of the bubble down, they join and the bubble disappears as the water above the bubble 'runs' down the wire.

Greg

[Jerry C]

Greg, that's the best explanation of how it works I've heard to date. Work it certainly does. I tried it but broke the glass accidentally later. When I replaced with new glass I forgot to put the wire back in. Am just waiting for another breakage and I won't forget next time. Another thought, water will block holes less than about 3/16" unless there is a pressure gradient. With the valve shut there is no  gradient. Do bubbles cause problems on larger diameter sight glasses? Jerry.

[rweust]

It works perfectly, no bubbles in operation with 50 PSI steam pressure. I tried this during a short sail in my pond today between the rain showers.

Sometimes you can see a drop of condensate comming down from the top of the water gauge, but the copper Litze wire and the movement of the model boat let the condensate flow nicely to the water level. No more bubbles and a big improvement, I can really recommend this when installing a water gauge.

Thank you for your great explanation Greg.

 

[gondolier88]

Do bubbles cause problems on larger diameter sight glasses? Jerry.

Hi Jerry,

As a rule, no, other than the ubiquitous 5/6mm glasses on our model boats which encounter the problem I have used 10mm & 12mm tube glasses and have never encountered the problem. I much prefer 'Reflex' type gauges to glass tube type in full size to be honest.

Greg

[KNO3]

I have used the wire in the glass tube method many times and it removes the bubbles reliably.